<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    let name = prompt('请输入你的姓名')
    let age = prompt('请输入你的年龄')
    let l = prompt('请输入你的长度')
    document.write(`大家好，我叫${name}，我今年${age}岁了，那个东西是${l}厘米`)
  </script>
</body>

</html>